(a) Field of the Invention
The present invention relates to an apparatus and a method for controlling vehicle stability. More particularly, the present invention relates to an apparatus and a method for controlling vehicle stability for stably controlling yaw behavior.
(b) Description of the Related Art
Generally, an apparatus for controlling vehicle stability includes a trace control system (TCS), an anti-lock brake system (ABS), and a vehicle dynamic system (VDS). An apparatus for controlling vehicle stability monitors a state of vehicle behavior on the basis of data measured from a yaw rate sensor detecting the vehicle behavior, a lateral acceleration sensor, wheel speed sensor, and steering angle sensor. The apparatus for controlling vehicle stability makes the vehicle stable by automatically controlling the vehicle behavior to meet a driver's intention. In a case that the state of the monitored vehicle behavior deviates from a target yaw rate determined by a steering angle and a vehicle speed, the apparatus for controlling vehicle stability generates a restituting yaw moment for maintaining stability. The restituting yaw moment is generally realized by differently controlling the left and right braking force. Since braking force is determined by a pressure of a caliper of a brake apparatus, a core aspect of controlling vehicle stability is controlling the brake pressure of respective wheels. Both, an open loop control method utilizing a table obtained by experiment or a closed loop method controlling the pressure after feedback of detecting the pressure of the caliper are known. Both methods, however, have shortcomings.
If the open loop control method is utilized, control performance may be poor, durability may be weak, and a brake pressure more excessive than a necessary pressure requested for controlling the vehicle may be supplied. If the closed loop control method is utilized, an additional pressure sensor should be mounted, costs increase, and in a case that the brake pressure sensor is out of order, the control system malfunctions.